Highly birefringent low-loss broadband polarization-maintaining hollow-core antiresonant fiber based on eccentric tubes

Highly birefringent low-loss (HBLL) polarization-maintaining hollow-core antiresonant fibers (PM-HC-ARFs) are of great interest for applications in fiber-optic communications, laser transmission, especially fiber sensing. However, conventional designs based on concentric tubes (CTs) often suffer from a fundamental trade-off between birefringence and loss. In this work, we propose an HBLL broadband PM-HC-ARF based on eccentric tubes (ETs). Structural models of ET configurations are constructed, and the mechanism of HBLL in ET Structures are analyzed using both the anti-resonant reflecting optical waveguide and inhibited coupling models. The fiber design results show that the ET structure with thicker walls near the core effectively decouples the loss-birefringence trade-off, enabling a significant expansion of the HBLL operational bandwidth by approximately 100 nm under the conditions of birefringence Δ<i>n</i> > 1 × 10^-5 and loss < 1 dB/m. Furthermore, the optimized fiber exhibits enhanced quasi-single-mode operation and bending performance compared to conventional CT-based designs. Fabrication tolerance analysis confirms that the proposed structure is robust to variations in key geometric parameters, underscoring its practical feasibility. This work demonstrates that HBLL broadband PM-HC-ARFs based on ETs are promising candidates for advancing high-performance PM-HC-ARF applications.